AIMTRON AT1309X

AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Feature
Description
•Operating Voltage:2.5V to 6.0V.
The AT1309 step-up converter is designed for small
or medium size LCD panel of high bias voltage with
a constant current to provide PDAs, and other
hand-held devices. It features a fast 1.4 MHz
current-mode PWM control with a built-in 0.3Ω
N-MOS that allows for smaller capacitor and
inductor. Fault condition protection uses cycle-by
-cycle current limiting to sense maximum inductor
current and thermal protection. Also included
soft-start eliminates inrush current during start-up.
•High Operating Frequency: 1.4MHz
•High Output Voltage: Up to 28V
•Shutdown Current <1µA
•Digital Dimming Control.
•Built-in Cycle-by Cycle Current-Limiting.
•Built-in Soft-Start Function.
•±1.5% 1.23V Reference Voltage
•Tiny SOT-25 Package
The AT1309 is available in 5-pin SOT-25 packages.
Application
• STN/OLED Bias
• Personal Digital Assistants(PDAs)
• DSC
Block Diagram
Aimtron reserves the right without notice to change this circuitry and specifications.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
1
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Pin Configuration
Ordering Information
Part number
AT1309X
AT1309X_GRE
Package
SOT-25
SOT-25, Green
Marking
Date Code
,Date Code with one bottom line
: Date Code
*For more marking information, contact our sales representative directly
Pin Description
Pin N0.
Symbol
I/O
Description
1
LX
I
Step-up Regulator N-MOS Drain. Place output diode and inductor.
2
GND
P
Ground
3
FB
I
4
EN
I
5
VIN
P
Step-Up Regulator Feedback Input. Connect a sense resistor from FB to
ground.
Enable and Dimming Control Input. LED brightness and IC shutdown are
controlled by the voltage on EN. Driving low for longer than 4ms to
shutdown the IC.
Power supply.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
2
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Absolute Maximum Ratings*1
Parameter
Rated Value
Unit
VIN voltage
-0.3 to +6.5
V
LX voltage
-0.3 to +30
V
EN , FB to GND
-0.3 to +6.5
V
Switch Current (ILX)
1.8
A
Continuous power dissipation (SOT-25 Ta=+25 C)
0.25
W
Operating Junction Temperature Range
-30 to 85
℃
Lead Temperature (Soldering 5 sec)
260
℃
Storage Temperature
-65 to 125
℃
Package Thermal Resistance (ΘJA)
250
O
ESD Susceptibility*2
HBM
2
MM
200
℃/W
KV
V
1. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. These are stress ratings only, and functional operation of the device at these or any other
conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure
to absolute maximum rating conditions for extended periods may affect device reliability.
2. Device are ESD sensitive. Handling precaution recommended. The Human Body model is a 100pF
capacitor discharged through a 1.5KΩ resistor into each pin.
Recommended Operation Conditions
Parameter
Symbol
Power supply voltage
VIN
Operating temperature
Top
Min.
Values
Typ.
Max.
2.5
─
6.0
V
-20
+25
+85
℃
Unit
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
3
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Electrical Characteristics
(VIN=2.5V, Ta=+25℃, unless otherwise noted)
Parameter
Symbol
Test Condition
Min.
Typ. Max. Units
Operating V IN Range
VIN
VIN input Voltage
2.5
-
6.0
V
Under Voltage Thershold
UVLO
VIN falling, 100mV hysteresis
2.1
2.2
2.3
V
Switch- Off Input Current
IIN1
No Switching
-
100
120
µA
Shutdown Current
IIN3
EN=0V
-
-
1
µA
Feedback Reference
VFB
FB Input Bias Current
IFB
Output Voltage Line Regulation
1.212 1.230 1.248
VFB =0.2V
2.5V< VIN <6.0V
V
-
-
1
µA
-
0.1
-
%
Switching Frequency
fOSC
-
1.4
-
MHz
Maximum Duty
DMAX
-
90
-
%
Soft-Start charging time
tSS
0.5
-
ms
Switching Current Limit
ILX
VIN=3.0V,duty cycle=80%
-
1.0
-
A
LX ON Resistance
RLX
ILX =350mA
-
0.3
-
Ω
LX Leakage Current
ILeakage
VLX =28V, EN=0V
-
-
1
µA
EN Input Current
IEN
EN=5V
-
-
8
µA
VIH
0.1V hysteresis
2.0
-
-
V
-
-
0.8
V
-
4
-
ms
-
120
-
℃
EN Input Level
VIL
EN low Shutdown Delay
Thermal Shutdown
-
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
4
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Typical Characteristics
Efficiency vs. VIN
Efficiency vs. Load current
100
96
98
Vo=15V
L=10uH
94
Vo=15V
L=10uH
96
94
92
92
Efficiency (%)
Efficiency (%)
90
90
88
86
88
86
84
82
80
84
78
VIN=3V
76
VIN=4V
82
IOUT=20mA
IOUT=50mA
IOUT=100mA
74
VIN=5V
72
80
70
10
20
30
40
50
60
70
80
90 100 110
2.5
3
3.5
Load current
4.5
5
5.5
6
VIN(V)
Quiescent current vs. VIN
Efficiency vs. Load current
90
200
190
Vo=15V
Vin=3.0V
89
180
88
170
TA=25OC
160
Quiescent current (uA)
87
Efficiency (%)
4
86
85
84
83
150
140
130
120
110
100
90
82
80
L=22uH
81
L=10uH
80
70
60
50
10
20
30
40
50
60
70
Load current
80
90
100 110
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]om.tw
5
6
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Load Transient Response
VIN=3.0V, Vout=15V, L=10uH, Iout=10mA to 100mA
Ch1:Vout (AC mode), Ch4:Iout, Time:0.2ms/div
Line Transient Response
VIN=3.0V to 6.0V, Vout=15V, L=10uH, Iout=100mA
Ch1:VIN, Ch2:Vout (AC mode), Ch3:IIN, Time:0.5s/div
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
6
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Start up Waveform with Load
VIN=3.0V, Vout=15V, L=10uH, Iout=100mA
Ch1:Vout, Ch2:EN, Ch3:IIN, Time:5ms/div
LX Switching Waveform
VIN=3.0V, Vout=15V, L=10uH
Ch1:LX, Ch3:ILX, Time:0.5us/div
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
7
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Application Circuit
MBR0530
-15V/4mA
1uF
1uF
4.7uH
MBR0530
1uF
VIN
2.5V to 5.0V
15V/4mA
MBR0530
4u7F
VIN
LX
MBR0530
20pF
1uF
AT1309
180K
FB
EN
16K
GND
Fig3. ±15V Dual Output Converter
10uH
15V/100mA
VIN
3.0V to 5.0V
SS24
10uF
VIN
LX
10uF
20pF
AT1309
180K
FB
EN
16K
GND
Fig4. 15V Boost Converter
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
8
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Function Description
The AT1309 is designed primarily for use in STN/OLED bias applications. The output
voltage of the step-up converter can be set from Vin to 26V with external resistive
voltage divider. The boost converter operates in current-mode PWM and a constant
frequency of 1.0 MHz. Depending on duty cycle of each switching cycle can regulate
output voltage. On the rising edge of the internal clock, the control and driver logic
block sets internal flip-flop when the output voltage is too low, which turns on the
N-MOS. The external inductor current ramps up linearly, storing energy in a magnetic
filed. Once peak current of inductor over trans-conductance output level, the N-MOS
turns off, the flip-flop resets, and external schottky diode turns on . This forces the
current through the inductor to ramp back down, transferring the energy stored in the
magnetic field to the output capacitor and load. To reduce external component amount,
the device will be built-in internal loop compensation.
Enable Control
Digital logic of EN provides an electrical ON/OFF control of the power supply.
Connecting this pin to ground or to any voltage less than 0.7V will completely turn
OFF the regulator. In this state, current drain from the input supply is less than 1µA,
the internal reference, error amplifier, comparators, and biasing circuitry turn off .
EN works as a simple on/off control. Drive EN high to enable the device, or drive EN
low for shutdown.
Soft-Start
Soft-start allows a gradual increase of the internal current-limit level for the step-up
converter during power-up to reduce input surge currents. As the internal current
source charges the internal soft-start capacitor, the peak N-MOS current is limited by
the voltage on the capacitor.
Cycle-by-Cycle Over-Current Protection
The AT1309 provides cycle-by-cycle over-current protection. Current limit is
accomplished using a separate dedicated comparator. The cycle-by-cycle current limit
abbreviates the on-time of the N-MOS in event that the current of flowing N-MOS is
greater than the current limit value. The current-limit feature protection against a hard
short or over-current fault at the output.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation in the AT1309. When the
junction temperature exceeds Tj=130 ℃, a thermal sensor activates the thermal
protection, which shuts down the IC, allowing the IC to cool. Once the device cools
down by 10 ℃, IC will automatically recover normal operation. For continuous
operation , do not exceed the absolute maximum junction-temperature rating of
Tj=120 ℃.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
9
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Power dissipation consideration
The AT1309 maximum power dissipation depends on the thermal resistance of the IC
package and circuit board, the temperature difference between the die junction and
ambient air, and the rate of any airflow. The power dissipation in the device depends
on the operating conditions of the regulator. In continuous condition, the step-up
converter power dissipated internally across the internal N-MOS can be approximated
by :
I × VO 2 1 Vin × D 2
) ] × RDS (ON ) × D
Pboost = [( O
) + (
Vin
12 f OSC × L
where
IO : It is the load current.
fOSC : It is a switching frequency.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
10
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Application Information
External components of boost converter can be designed by performing simple
calculations.
Boost inductor
Inductor selection depends on input voltage, output voltage, maximum output current,
switching frequency and availability of inductor values. The following boost circuit
equations are useful in choosing the inductor values based on the application. They
allow the trading of peak current and inductor value while allowing for consideration
of component availability and cost.
The peak inductor current is given by:
I Lpeak = I LAVG +
I LAVG =
∆I L
2
IO
1− D
where:
△IL is the inductor peak-to-peak current ripple and is decided by:
V
D
∆I L = in ×
L
f OSC
D is the MOSFET turn on ratio and is decided by:
V −V in
D= O
VO
fOSC is the switching frequency.
The inductor should be chosen to be able to handle this current and inductor saturation
current rating should be greater than IPEAK.
Diode selection
The output diode has average current of IO, and peak current the same as the
inductor’s peak current and a voltage rating at least 1.5 times the output voltage.
Schottky diode is recommended and it should be able to handle those current.
Output Capacitor
The AT1308 is specially compensated to be stable with capacitors which have a worstcase minimum value of 1uF at the particular VOUT being set. Output ripple voltage
requirements also determine the minimum value and type of capacitors. Output ripple
voltage consists of two components the voltage drop caused by the switching current
through the ESR of the output capacitor and the charging and discharging of the
output capacitor:
V − Vin
IO
VRIPPLE = I LPEAK × ESR + O
×
VO
COUT × f OSC
For low ESR ceramic capacitors, the output ripple is dominated by the charging or
discharging of the output capacitor.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
11
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Impacting frequency stability of the overall control loop, Ceramic capacitors are
preferred on the output capacitance, but tantalum capacitor may also suffice. If it use
tantalum capacitor on the output terminal, that in addition the capacitance parallel
with feedback resistor network is necessary. These frequency response effects
together with the internal frequency compensation circuitry of AT1308 modify the
gain and phase shift of the closed loop system.
PCB layout guidelines
Careful printed circuit layout is extremely important to avoid causing parasitical
capacitance and line inductance. The following layout guidelines are recommended to
achieve optimum performance.
‧ Please the boost converter diode and inductor close to the LX pin and no via.
Keep traces short, direct, and wide.
‧ Please ceramic bypass capacitors near the input/output pin.
‧ Locate all feedback sense resistors as close to the feedback pins as possible.
‧ The ground connections of VIN and VOUT should be as close together as possible.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
12
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Small Outline SOT-25
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
13
AT1309
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Reflow Profiles
Profile Feature
Sn-Pb Eutectic Assembly
Large Body
Small Body
Pkg. thickness
Pkg. thickness
<2.5mm or Pkg.
≥2.5mm or Pkg.
3
volume ≥350mm3 volume <350mm
Average ramp-up rate
(TL to TP)
Preheat
-Temperature Min(Tsmin)
-Temperature Max (Tsmax)
-Time (min to max)(ts)
Tsmax to TL
-Ramp-up Rate
Time maintained above:
-Temperature (TL)
-Time (tL)
Peak Temperature(TP)
Time within 5°C of actual Peak
Temperature (tP)
Ramp-down Rate
Time
25°C
to
Peak
Temperature
3°C/second max.
Pb-Free Assembly
Large Body
Small Body
Pkg. thickness
Pkg. thickness
≥2.5mm or Pkg.
≥2.5mm or Pkg.
volume ≥350mm3 volume ≥350mm3
3°C/second max.
100°C
150°C
60-120 seconds
150°C
200°C
60-180 seconds
3°C/second max.
183°C
60-150 seconds
217°C
60-150 seconds
225+0/-5°C
10-30 seconds
240+0/-5°C
10-30 seconds
6°C/second max.
6 minutes max.
245+0/-5°C
10-30 seconds
250+0/-5°C
20-40 seconds
3°C/second max.
8 minutes max.
*All temperatures refer to topside of the package, measured on the package body surface.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.1
Email: [email protected]
14